Justification:
Based on habitat loss alone, this species is considered Vulnerable in that at least 30% of the habitat has been converted in the past 20 years (approximately 3 generations). From 1990 to 2000, about 15-26% of the forest habitat on the island was converted to agriculture (A. Salim pers. comm.), and since that time at least an additional 10% has been lost. This listing is further justified by the fact that the taxon will be subdivided in the future and that some of the populations will have much greater threats than others.

T. tarsier, sensu lato, has an estimated extent of occurrence of 149,136 km2. Within this are 1,782 km2 of old growth forest and 33,980 km2 of good habitat, yielding an estimate of 35,852 km2 of tarsier habitat that is considered good or better. Additionally, there are 27,528 km2 of fair habitat. This produces an estimate of 63,380 km2 of potentially usable tarsier habitat. Assessed in the broad sense, T. tarsier is easily the least endangered tarsier found in Wallacea. On the other hand, T. tarsier, sensu stricto is sympatric with Macaca maura, and by analogy is likely to be highly threatened. Thus, under the current taxonomy T. tarsier should be considered to have a conservation status of no greater than Vulnerable and possibly as little as Least Concern, but in the more restricted sense it would likely be a candidate for Critically Endangered. This example illustrates the urgent need for more taxonomic work on Sulawesian tarsiers. The problem is not trivial, since at least 17 potentially new taxa have been discovered within the population of tarsiers that Niemitz (1984) classified as a single subspecies. This is particularly true since, owing to the conservation threats to some of the smaller populations with restricted ranges, there is the possibility that they may go extinct before they have even been named. This is turn argues in favor of the most conservative conservation estimate that can be justified for T. tarsier.

By definition, T. tarsier is the rump taxon of tarsiers that remain in the Sulawesi biogeographic region, after excluding T. sangirensis, T. pumilus, T. dentatus, T. pelengensis, and T. lariang. This leaves T. tarsier, sensu lato, with an unlikely distribution that includes Sulawesi, Buton, Muna, Kabaena, Selayar, and the Togian Islands, below 1,800 m (with an actual vertical distribution that likely stops somewhere between 1,100-1,500 m), except those portions of Sulawesi that lie within the ranges of T. dentatus and T. lariang. As discussed by Brandon-Jones et al. (2004), this is distribution is improbably disjunct. It is more likely that this population is subdivided into numerous insular and parapatric species, as hypothesized by Shekelle and Leksono (2004) and Brandon-Jones et al. (2004).

Within T. tarsier, sensu lato, the best studied population comes from Tangkoko, which is at the extreme northeast peninsula of Sulawesi, whereas Makassar, the type locality of T. tarsier sensu stricto, is at the extreme southwestern peninsula, and has not been the subject of systematic study. Population density estimates at Tangkoko are 70/km2 (MacKinnon and MacKinnon 1980) and 156/km2 (Gursky 1997). Merker (2003) estimated population densities for T. dentatus in a variety of pristine and human disturbed habitats near Kamarora, on the edge of Lore Lindu National Park. The values he calculated were 270/km2 in pristine habitat, 190/km2 for slightly disturbed, 130/km2 for moderate disturbance, and 45/km2 in heavily disturbed habitat.

Tarsius tarsier sensu stricto has not been the subject of systematic study, but by analogy with wild tarsier populations studied at Tangkoko and with T. dentatus at Lore Lindu National Park, it is expected that this taxon is found in primary, secondary and mangrove forests, forest gardens, and a variety of other habitats of varying degrees of human disturbance that provide adequate shrubby cover. It shows extreme adaptations for vertical clinging and leaping (VCL) in the understory of suitable tropical habitats, often 2 meters or less from the ground. Nocturnal social primates, they likely live in small, monogamous or polygamous groupings of 2-6. The home range is believed to be less than one hectare. Its diet is 100% live animal prey, mostly insects with some small vertebrates.

Major threats include habitat loss due to agriculture, illegal logging, mining of limestone for cement manufacture, agricultural pesticides, and predation by domestic animals (dogs and cats). Some animals are entering the pet trade (particularly from North Sulawesi, around Tankoko). Although there has been extensive loss of habitat, this species, however, has demonstrated some tolerance to forest conversion. Although seemingly among the least threatened of tarsiers owing to its relatively wide distribution, the possible existence of undescribed cryptic species makes it likely that some populations are more threatened than others. This species should be reassessed upon further taxonomic revision.

Tarsiers are protected by international treaties, including CITES Appendix II, as well as by national law. Many portions of the range of this taxon are within conservation areas, but there needs to be improved management of these areas to ensure the continued survival of the species. Public education to overcome the misconception that tarsiers are crop pests would be a step forward in improving conservation measures. Indeed, the species might actually be beneficial to crops, as they eat, and may even have a dietary preference for, some of the real crop pests such as large grasshoppers.